This invention relates to rotary internal combustion engines and more particularly to improved apex seals therefore.
In conventional rotary engines, apex seals are mounted in slots in the rotor. Gas pressure acts on the bottom of the seal and pushes the seal radially outwardly towards sealing engagement with the running surface of the engine housing.
The operating pressures in the working chambers are different from one another so that there is a differential pressure across each apex seal between each two adjacent chambers which urges the apex seal against one side wall and away from the opposite side wall of its apex slot.
Friction between the apex seal and the one slot side wall can interfere with the rapid radial movement of the apex seal which is required for the apex seal to maintain sealing engagement with the running surface. As described in U.S. Pat. No. 3,185,387, it has been proposed to reduce this frictional force by having a passage or passages which extend through the apex seal in the circumferential direction in order to reduce the differential pressure which urges the apex seal into engagement with a side wall of the slot.
However, the apertures in such a design increase the volume exposed to the under seal gas pressure, thus increasing the amount of time required for changes in the under seal pressure to produce corresponding radial movement of the apex seal. This reduces the ability of the apex seal to maintain effective sealing engagement with the housing running surface.